Initial work focused on the effects of administering deuterated L- dopa on non-deuterated catecholamines, then shifted towards comparing central and peripheral metabolism of D-dopa with that of L-dopa. Finding that D- and L-dopa give rise to dopamine by about the same efficiency, we characterized these amino acids biochemically and behaviorally. We carried out additional experiments that explored the underlying mechanisms responsible for forming dopamine from D-dopa. This work completed and terminated the project. The results were published.